A high percentage of wireless communications is conducted with a mobile device located inside a building, while the wireless communications networks are conventionally implemented such that the cellular antennas are located outside of buildings. Inherent with in-building penetration of cellular signals is an attenuation of the cellular signal strength. Thus, the attenuation of signal strength may result in a lack of, or reduced, communications coverage while the mobile device is located inside of a building. For example, the user of a mobile device may be unable to place or receive a telephone call while inside a house or office building.
One device used to compensate for weak cellular signals within a building is known as a home base station, also known as a femtocell. Home base stations are typically stand alone units deployed within a building, such as an office, a place of business, or even a home. These home base stations provide two-way wireless voice and data communications coverage for a mobile device, thereby extending the effective coverage area for the communications network. The home base station supports cellular calls locally, and then uses a broadband connection to carry traffic to the communications network. One advantage of a home base station is that they typically operate with existing mobile devices rather than requiring users to use a separate phone or even upgrade to an expensive dual-mode device.
Successful operation of a handoff of a mobile device between base stations depends on the stability and synchronization of the internal clocks of respective base stations. In particular, in order for respective base station and mobile device transmissions to stay locked to each other, the internal clock of the current base station must be synchronized with the internal clock of the base station to which the mobile device is being handed off. In addition, synchronization of one base station with a communications network reduces the likelihood that communications between the base station and a mobile device will interfere with other communications on the same network.